As a long term goal, we seek to contribute to a better understanding of bilingual language production, specifically looking at the ways in which bilinguals meet the challenge of successfully negotiating between two languages and also mapping out the ways in which their language production differs from how monolinguals speak. In this research proposal, we investigate the mechanism underlying a previously identified bilingual effect, specifically, that bilinguals produced fewer correct responses in a verbal fluency task than monolinguals, particularly when the task required retrieval from meaning based (i.e. semantic) categories (e.g., animals). Although this pattern of performance resembles that observed in monolinguals with early-stage Alzheimer's disease, we hypothesize that the bilingual effect on fluency arises because of cross-language interference;and that the bilingual effect will be greater when cross language interference is more difficult to control (i.e., in aging, and Alzheimer's disease). To test this account, we propose to compare semantic verbal fluency task performance, across young, older, and cognitively impaired bilinguals and monolinguals. To examine how bilinguals differ from monolinguals, we we examine number of correct responses, reaction time to first response, and mean response latency. If the bilingual effect arises because of cross language interference, we predict that bilinguals will have fewer number correct than monolinguals, slower first response reaction times, and slower mean response latencies. Additionally, we predict that the size of the bilingual disadvantage will increase with both age and Alzheimer's disease. These studies will help elucidate the extent to which bilinguals rely on general mechanism of cognitive control to language selection as well as help to characterize what effects aging and Alzheimer's disease have on the bilingual population.